Am I allowed to resent couples?

I remember reading, in one of the books about romance novels that I've been going through for my Legally Blonde/romance novel analysis paper, a passage from an old-ish romance novel. Some supposedly wiser, and certainly older, woman was advising the young heroine. She was talking about how women in love are happier to see other couples. I believe the term she used was “more generous.” She was essentially saying that women are more complete, more selfless, and more understanding of others as long as they're in (reciprocal) love. And in this case, it's worth pointing out that love denotes coupledom. I caught myself wondering about that idea today.

I was on my way home from the store, the weather was fantastic (for February in Montreal, at least) and I felt great. I turned onto a side street and was immediately confronted by the sight of a couple kissing as they walked. My instinct was to resent, if not them, then at least their public display of affection. My second reaction was to wonder why I was resenting them and their display. Am I allowed to be displeased by people who kiss in public? Am I merely resenting them because they are displaying their status as a unit? Does the wisdom from the romance novel apply? Would I stop resenting their display if I were part of a unit?